Field of the invention
The present invention relates to a technology relating to a burner device to be used as a constitutional element of a water heating apparatus.
Description of the Related Art
One embodiment of a burner device is disclosed in Patent Literature 1.
In the burner device, a plurality of burner bodies, referred to as a burner head or a combustion tube, are housed in a burner case and the heating power is controllable. The burner case is a substantial cuboid which is made of a metal plate and has a top opening, and a heat exchanger is provided on the burner case. When the burner body is driven for combustion, combustion gas passes through the top opening and flows toward the heat exchanger. The burner case is constituted by a case body and a cover, the case body having a rear opening in addition to the top opening, the cover closing the rear opening. The rear opening is used for incorporating the burner body into the case body.
In such a burner device, it is necessary to prevent gas in the burner case from leaking outside. Conventionally, a flange portion is provided along the rear opening of the case body, a sealing packing is interposed between the flange portion and the cover, and the cover is screwed at plural points to the flange portion.
However, in the related art, the cost for a sealing packing is required in addition to the cost for screwing members, thereby increasing the material cost of the burner case. In addition, a screwing operation is complicated and its productivity is not so high. Thus, there is such a disadvantage that the production cost of the burner case and also the production cost of the burner device increase.